Rivet gun



FIG. 1 is an elevational view of a rivet gun showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is an end view looking from the left with respect to FIG. 1; and

FIG. 5 is an end view looking from the right with respect to FIG. 1. 

The ornamental design for a rivet gun, substantially as shown. 